Thanks for the discussion, folks! Let me clarify a few things.

First, I asked here on FT because I was looking for someone with personal experience. Of course looked on the web a bunch starting as soon as I got flashed - do they have speed cameras here in Tucson? - and got plenty of info before I asked anything. But FTer's are everywhere and do everything travel; so many times I've gotten amazing first person info about things ranging from fares to hotels to how to walk out of the airport (DCA). So I thought I'd try here.

Second, this was in Arizona, which may have gotten lost in some of the conversation. So Arizona statutes and case law would apply. Things may be completely different in other states, I have no idea.

Third, I have learned here about the cross-state compact and how my state of residence is not a member, so this is good news to me and limits the damage.

Fourth, small point, my rental was with Hertz, not Avis, but I posted here because where I got hits when I searched on FT. I would imagine they behave the same. Hertz gets the notice from Pima County, they respond with my name, they charge me $30. If the owner of the car is not the driver, they should not have further responsibility, and I certainly expect the car rental company to come and get me for any further charges they incur (they do have my CC number, and of course the terms of the contract would indicate they have the right to.)

I'm probably going to ignore the date on the initial summons, do nothing that would give them evidence that I got it (like check the web site they give to see the full set of photos and vids), and then check the court records after the date to see how it was disposed. But there is an Arizona lawyer who has published some info in a small book that I might buy just to get further info. Whatever decision I make will be well reasoned. The stakes are much lower now that I understand it won't get me hit with an insurance surcharge.

Again, thank you for the comments, much appreciated.